There’s more trash in the Atlantic Ocean than in the three Dumpsters that a city group has converted into swimming pools in Brooklyn for the summer.

Bleached, cleaned, filled with sand and lined with plastic, the giant trash bins are now the centerpiece of a “low-fi country club,” said David Belt, who as president of Manhattan-based Macro Sea is the man behind this Dumpster-diving project.

The pools, which Macro Sea debuted on July 4 in an otherwise abandoned Gowanus lot it has rented through the end of August, are not open to the public, but those in the know say swimming in trash containers is mentally sanitizing.

Two of the 8-foot-wide, 22-foot-long pools are 6 feet deep, and the third is 4 feet deep.

This is hardly swimming in sewage, Belt said. The untreated, nonchlorinated water is as pure as on a Caribbean beach.

A water company filled the pools with 18,600 gallons of water, which cost Macro Sea $1,200.

The group — which hopes to expand with even bigger Dumpster pools next year — also installed a bocce court, lounge chairs, eight grills, two lounging cabanas with hanging lanterns and a small changing cabana.

“We have these preconceived notions about things, like you’re not supposed to swim in a Dumpster, but when people jump in they have a really good time,” said creative director Jocko Weyland.

“You can make something out of existing elements. This is a really lovely place. It’s not just a Dumpster. It’s hot in New York, you’re in your tiny little apartment, but then you can come to the urban country club.”

The friends, relatives and neighbors who have had a chance to Dumpster-dive say it’s a unique thrill.

“I was mystified by the idea of a Dumpster pool, but it’s really cool, and the water is perfect,” said Isabella Hill, 22, who lives nearby.

“It’s so hot out, and this is a convenient swim location, even though it’s in a Dumpster.”

Macro Sea’s mission is to find ways to reuse old materials.

“Unutilized spaces are dead. But using spaces this way injects energy into the community,” said Belt, who is working to turn old strip-mall sites into public parks.

The pools are “a prototype for a larger project,” he said.

For the time being, Macro Sea is hosting parties and small events like film screenings and lectures at the Dumpster pools.

The Dumpsters were donated to the group by a contractor and will return to their usual function after the summer.

“They had extra Dumpsters because construction projects have slowed with the economy,” Belt said.